On EX4300-MP Series devices with any lo0 filters applied, transit network traffic may reach the control plane via loopback interface (lo0). The device may fail to forward such traffic.

This issue affects Juniper Networks Junos OS 18.2 versions prior to 18.2R1-S2, 18.2R2 on EX4300-MP Series.

This issue does not affect any other EX series devices.

This issue requires filters configured on lo0.

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

This issue was found during internal product security testing or research.

This issue has been assigned  CVE-2019-0041 .

The following software releases have been updated to resolve this specific issue: 18.2R1-S2, 18.2R2, 18.3R1, and all subsequent releases.

This issue is being tracked as PR  1379328  which is visible on the Customer Support website.

Note: Juniper SIRT's  policy  is not to evaluate releases which are beyond End of Engineering (EOE) or End of Life (EOL).

Software Releases, patches and updates are available at  https://www.juniper.net/support/downloads/ .

Removing lo0 filters would mitigate this issue.

• 2019-04-10: Initial Publication.

• KB16613: Overview of the Juniper Networks SIRT Quarterly Security Bulletin Publication Process. [juniper.net]
• KB16765: In which releases are vulnerabilities fixed? [juniper.net]
• KB16446: Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories [juniper.net]
• Report a Security Vulnerability - How to Contact the Juniper Networks Security Incident Response Team